The objective of this research is to investigate the effectiveness of electrocutaneous sensory feedback as an aid to the patient in controlling upper extremity artificial limbs. Important accomplishments of the research have been the following: 1) Construction and preliminary evaluation of an experimental prosthesis which can be used as a research tool for evaluating electrocutaneous sensory feedback; 2) Development of practical surface electrocutaneous stimulators; 3) Refinement of proportional controllers necessary for properly assessing the value of sensory feedback signals from externally energized prosthetic components; 4) Investigation of hand position and grasp force sensory feedback signals; and 5) Exploration of the undesired interaction in simultaneous EMG controlled electrocutaneous feedback prostheses. The following research is planned for 1975: (1) Evaluation of effectiveness of sensory feedback signals proportional to: a) Elbow flexion and extension; b) Wrist pronation and supination; c) Grasped object temperature; d) fingertip touch (on-off signals); e) Limb loading. (2) Investigation of the relative importance of sensory feedback parameters. (3) Determination of how many sensory feedback dimensions can be effectively presented to the patient at the same time. (4) Ascertainment of how these dimensions can be optimally coded for presentation. (5) Further investigation of undesired interaction in simultaneous EMG controlled electrocutaneous sensory feedback prostheses. (6) Refinement and evaluation of various electrode and stimulation circuits. (7) Exploration of practical "add-on" sensory feedback systems for conventional cable operated prostheses.